Welcome! Becoming a registered user of ShortWingPipers.Org is free and easy! Click the "Register" link found in the upper right hand corner of this screen. It's easy and you can then join the fun posting and learning about Short Wing Pipers!

Thanks Thanks:  0
Page 2 of 3 FirstFirst 123 LastLast
Results 11 to 20 of 21

Thread: Fabric Test

  1. #11
    Stephen's Avatar
    Join Date
    Nov 2007
    Location
    Lopez Island, WA
    Posts
    4,140
    Post Thanks / Like

    Default Re: Fabric Test

    Quote Originally Posted by Tnathan View Post
    Interesting discussion. I thought it would be nice to have a tester that could give me an objective measure of fabric life. But as I looked into it, punch tests seemed controversial. And now with Dacron/polyfiber, i was told the fabric is not the shortest time limited component any more. I keep mine in a hanger minimizing uv and rain/snow/ice to protect it. I don’t recall where this crawled into my head but I thought someone said well maintained Dacron fabric should last 30 years. So the whole idea of having an a&p taking an ice pick to my fabric annually has paled for me.

    Actually I was told the new issue will be that fabric can stay on too long concealing corrosion issues that would have been historically identified when the shorter life cotton would have failed. I wonder if folks will actually start removing serviceable fabric to inspect/repair corrosion. Haven’t heard anyone say so but is Interesting to think about.


    Sent from my iPhone using Tapatalk
    No ice picks or punch tests are done anymore. The Maul test does not penetrate the fabric.....unless it is totally rotted.

    I have Dacron fabric on my plane that is more than 30 years old and is fine.
    "You can only tie the record for flying low."

  2. #12
    Subsonic's Avatar
    Join Date
    Mar 2016
    Location
    Merritt Island, FL
    Posts
    1,180
    Post Thanks / Like

    Default Re: Fabric Test

    Quote Originally Posted by Stephen View Post
    This author says TSO C-15, 14 are still in play regardless of the type of fabric. He also says the old Seyboth punch tester has been replaced by the Maule. I bought my Maule tester in the early 70's but, have not used it since Dacron has been the standard. But, I find this interesting. He does point out that he does NOT use the tester unless the bright light shows through from the inside the fabric.
    I too, find this discussion interesting. If the author uses a light, I'd ask him what band-pass (spectral interval) in the electromagnetic spectrum, and what intensity. And, I'd ask if that is documented in any standard or formal requirement.

    The human eye senses light in the Visible part of the spectrum. Approximately 0.4 to 0.7 Nanometers. Or, 400 to 700 Micrometers (microns).

    I've read that Dacron is sensitive to UV light, wavelengths shorter than 0.4 nM. The human eye doesn't see in the ultraviolet. Bees do, and hummingbirds, etc. Humans don't. So, our human author is using a vague, non-quantitative method for determining areas of concern.

    A "bright light" is not quantitative for determining optical opacity of any material. Qualitative at best.

    It matters how close the light is to the material because the fall off in radiant intensity varies as the inverse of range squared. To measure optical opacity of any material, you must state the spectral interval of your light source, the radiant intensity in that interval, the distance from the material, and then you must use a calibrated radiometer on the other side at a known distance from that material.

    Then, you have to ask what an acceptable loss or attenuation factor (opacity) is, for an adequately coated/painted fabric, for that light source. All of these criteria would have to be documented somewhere, so that standards could be maintained from one plane to the next over time.

    He might be onto something, though. If the coatings have deteriorated to the point where visible light shines through readily, its probably a good bet that UV is getting through since those shorter wavelengths are more energetic than visible light.

    Next, There are also large areas of the plane where the human eye would have trouble getting, to see if a bright light shined through. But you might be able to position small radiometers in various places however by poking or dragging them in place like you would with a borescope.

    -Subsonic

  3. #13
    Stephen's Avatar
    Join Date
    Nov 2007
    Location
    Lopez Island, WA
    Posts
    4,140
    Post Thanks / Like

    Default Re: Fabric Test

    Geez Sub, had to read it more to once to get all you points. You've been thinking.
    "You can only tie the record for flying low."

  4. #14

    Join Date
    Mar 2017
    Location
    Frederick MD
    Posts
    1,947
    Post Thanks / Like

    Default Re: Fabric Test

    Just as a follow on to this discussion, when I was learning about dope and fabric, along about the time Ceconite came out (mid 1960s), my mentor (my father) taught me to put a drop light (60 watt, but be careful it doesn’t contact the fabric) inside the wing or fuselage in a darkened room. If you could see the light through the fabric, spray a couple more coats of silver until you can’t see it. That’s pretty much how I have done it ever since.


    Sent from my iPad using Tapatalk

  5. #15
    Stephen's Avatar
    Join Date
    Nov 2007
    Location
    Lopez Island, WA
    Posts
    4,140
    Post Thanks / Like

    Default Re: Fabric Test

    Quote Originally Posted by dgapilot View Post
    Just as a follow on to this discussion, when I was learning about dope and fabric, along about the time Ceconite came out (mid 1960s), my mentor (my father) taught me to put a drop light (60 watt, but be careful it doesn’t contact the fabric) inside the wing or fuselage in a darkened room. If you could see the light through the fabric, spray a couple more coats of silver until you can’t see it. That’s pretty much how I have done it ever since.


    Sent from my iPad using Tapatalk
    I learned the same in the 70's. Although, this does not apply to Stewart System. They strictly go by coats. If you have your plane outside and look from the inside light does come through.

    I'm not sure how much of any of this discussion matters if your plane is hangered.
    "You can only tie the record for flying low."

  6. #16

    Join Date
    Nov 2007
    Location
    Beagle, Oregon (Medford) United States
    Posts
    1,308
    Post Thanks / Like

    Default Re: Fabric Test

    It would not surprise me that sometime in the near future there will be ruling out in place to where fabric covered airplanes “must” be re covered after X amount of years in service to check for structural degradation due to rust and/or rotting wood.

    We have a Tri-Pacer that was last covered with Dacron in 1968… fabric still punches just fine… looks like hell, but that rag is perfectly good.. More than likely I will be stripping it off just to check that tubing underneath someday..

    I have the outer wing panels for a Fournier RF5B motor glider in my shop now that I stuck my thumb through the bottom skin when I was doing it’s inspection last year… It is a hanger queen, but covered in its original linen from the factory in 1973..

    Brian

  7. #17
    Stephen's Avatar
    Join Date
    Nov 2007
    Location
    Lopez Island, WA
    Posts
    4,140
    Post Thanks / Like

    Default Re: Fabric Test

    Brian,

    How do you do your fabric inspections?
    "You can only tie the record for flying low."

  8. #18

    Join Date
    Nov 2007
    Location
    Beagle, Oregon (Medford) United States
    Posts
    1,308
    Post Thanks / Like

    Default Re: Fabric Test

    Quote Originally Posted by Stephen View Post
    Brian,

    How do you do your fabric inspections?
    Maule tester, light through fabric. Etc… More than anything I look for signs of bad structure.. rust bubbles in the lower longerons, cracks in wood spars and gear fittings.. wood rot.. stuff like that.. the before mentioned motor glider would punch fine in certain areas.. put my finger through it near a drain grommet.. the owners knew it was getting about time so was expecting me to ground it for re cover..

    Brian

  9. #19
    Stephen's Avatar
    Join Date
    Nov 2007
    Location
    Lopez Island, WA
    Posts
    4,140
    Post Thanks / Like

    Default Re: Fabric Test

    Quote Originally Posted by stevesaircraft(Bri) View Post
    Maule tester, light through fabric. Etc… More than anything I look for signs of bad structure.. rust bubbles in the lower longerons, cracks in wood spars and gear fittings.. wood rot.. stuff like that.. the before mentioned motor glider would punch fine in certain areas.. put my finger through it near a drain grommet.. the owners knew it was getting about time so was expecting me to ground it for re cover..

    Brian
    Thanks Brian.

    I think I might drag out my Maule tester.
    "You can only tie the record for flying low."

  10. #20
    Glen Geller's Avatar
    Join Date
    Dec 2007
    Location
    Beaverton, Oregon, United States
    Posts
    1,462
    Post Thanks / Like

    Default Re: Fabric Test

    Sorry Sub, but I think you have your units backwards.

    "Approximately 0.4 to 0.7 Nanometers. Or, 400 to 700 Micrometers (microns)." This is incorrect.

    1000 nm = 1 um
    700 nm = 0.7 um

    https://www.gigacalculator.com/conve...micrometer.php

    Typically, the human eye can detect wavelengths from 380 to 700 nanometers.
    https://science.nasa.gov/ems/09_visiblelight

    But we can all agree that Shortwing Pipers are the finest airplanes known to humankind!


    Best,
    GG

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •